A virtual test-bed for the prediction of holistic effective elastic properties of UD composites

Most existing computational approaches are restrictive in their predictive capabilities by using non-representative virtual geometric domains (RVEs) of test materials. The strategy proposed here relaxes these restrictions by utilizing statistically representative 3D RVEs with appropriate boundary conditions and a robust homogenization implementation based on a micromechanical modelling philosophy. The strategy was implemented as a self-consistent, rigorous, virtual testing framework analogous to a physical experimental testing scheme. The strategy proposed in this work was shown to give a holistic set of elastic properties of the test composites considered when compared with other predictive approaches. Also, parametric studies were carried out to explore the different features of the virtual framework. Therefore, this virtual test-bed strategy represents a suitable substitute for realistic experiments and can be used in designing different virtual experiments

Virtual Testing Architecture for Prediction of Effective Properties of Particulate Composites

This study has developed a computational virtual testing architecture for predicting effective properties of particulate composites. A particulate composite made up of SiC filler in an alumina matrix was used in this work. The test composite was modelled first by considering perfect bonding between the matrix and filler constituents and subsequently the effect of interphase region was assessed too

FINANCIAL DEVELOPMENT AND ECONOMIC GROWTH: A CAUSAL ANALYSIS

This study sought to analyze the nature of the causal relationship that prevails in the two largest economies in Sub-Saharan Africa- Nigeria and South Africa between 1996 and 2020. The study follows the recommendations of the World Bank Global Financial Development index, to measure financial development from its four dimensions, by institutions and markets. These include depth (money supply and stock market capitalization), access (bank branches and value of stocks outside top ten), efficiency (interest rate spread and stock turnover), and stability (capital to asset ratio and stock price volatility). These served as the explanatory variables. The explained variable is gross domestic product growth rate as a measure of economic growth. The Granger causality test is employed for analysis. The results reveal that only in South Africa did a unidirectional causal relationship exist, flowing from economic growth to financial stability (stock price volatility). In the case of Nigeria, no causal relationship was found. The study concluded that demand-following financial development was what prevailed in South Africa, while the Independent stage hypothesis holds in Nigeria. The study recommended that more financial instruments and products such as mobile banking schemes be created and made available to help mop more cash in circulation into the formal financial system. Also, growth board schemes initiated to encourage the listing of companies with high growth potential on the exchange must be enhanced

A constitutive model for semi-crystalline polymers: A multiple viscoelastic relaxation processes implementation.

The constitutive modelling of semi-crystalline polymers seeks to obtain reliable predictive tools for a wide range of their mechanical responses. Such efforts have continued to occupy computational material scientists. Although significant advances have been made regarding amorphous polymers, thanks to works by Buckley [1], Boyce [2], and Govaert [3], there is significant research scope for developing similar predictive modelling fidelity for semi-crystalline polymers. The presence of crystalline and amorphous phases in semi-crystalline polymers presents interesting constitutive modelling challenges. In this study, a physically based, three-dimensional constitutive model has been developed for simulating a wide range of features observed in deformation and processing of semi-crystalline polymers. The constitutive mathematics is based on a one-process Grass-Rubber model for amorphous polymers proposed by Buckley and colleagues [1]. The model philosophy exploits the presence of multiple relaxation processes associated with the different mechanics of the crystalline, amorphous and pseudo-amorphous parts of the polymer. The model development reasoning is inspired by a well-known physical framework of rate-dependent deformation that establishes a correlation between the observed transition in flow stress of a material and the secondary β-transition of the viscoelastic behaviour. Here, two dominant relaxation processes were identified - the α- and the β-processes. Each process was modelled using the bond-stretching and conformational stresses constitutive mathematics of the Glass-Rubber model. The model has been implemented numerically into a commercial finite element code through a user-defined material subroutine (UMAT) and validated against compression test results carried out on an isotactic polypropylene across an unusually wide range of strain rates [4]. In this study, the model predicts quite well the experimentally observed nonlinear mechanical responses like: temperature and rate-dependence, adiabatic heating effects, structural rejuvenation and post-yield de-ageing of polypropylene. It provides a viable modelling tool that can be utilized for design involving semicrystalline polymers at room temperature as well as exploring the processing response at elevated temperatures

FINANCIAL DEVELOPMENT AND ECONOMIC GROWTH: A COMPARATIVE ANALYSIS OF NIGERIA AND SOUTH AFRICA

Advances in the financial system have been acclaimed to improve economic growth, drawing from theories of the latter. This study set out to test this hypothesis with respect to financial institutions and markets in the two largest economies of Sub-Saharan Africa. Economic growth for both countries is measured by gross domestic product annual growth, as the explained variable. Financial development is measured by institutions and markets. The dependent variable by financial institutions includes money supply, bank branches, interest rate spread, and bank capital to asset ratio. For financial markets, market capitalization, traded value excluding top 10 traded companies to total traded value, market turnover, and stock price volatility. Data is obtained from the World Bank for both countries. Two models are developed, one for each country. For analysis, the Augmented Dickey-Fuller unit root test, and autoregressive distributive lag are employed. The results indicated that of all variables considered only money supply (financial depth by the institution) had a significant, yet negative influence on economic growth in Nigeria. No dimension of financial development is related to output in the long term for South Africa. The study inferred that financial development in both countries is yet to advance sufficiently to make desired effect on economic growth. Expansion of financial institution market and institutions in the form of exchange growth scheme (for small and medium businesses) and rural bank branching was recommended by the study

Investigation of slug mitigation: self-lifting approach in a deepwater oil field

Slug flow is a flow assurance issue that staggers production and, in some cases, 'kills the flow' of the well. Severe slugging, a type of slugging which usually occurs at the base of the riser column, causes large amplitudes in the fluctuation of pressure within the riser column and consequently damages equipment placed topside. An adaptation of a novel concept to slug mitigation: the self-lifting model, is presented. This model presents variations to the internal diameter of the self-lift bypass to produce effective mitigation to severe slugging

Adiposity and weight change in mid-life in relation to healthy survival after age 70 in women: prospective cohort study

Objective: To examine the hypothesis that mid-life adiposity is associated with a reduced probability of maintaining an optimal health status among those who survive to older ages. Design: Prospective cohort study. Setting: The Nurses’ Health Study, United States. Participants: 17 065 women who survived until at least the age of 70, provided information on occurrence of chronic disease, cognitive function, physical function, and mental health at older ages, and were free from major chronic diseases at mid-life (mean age was 50 at baseline in 1976). Main outcome measures: Healthy survival to age 70 and over was defined as having no history of 11 major chronic diseases and having no substantial cognitive, physical, or mental limitations. Results: Of the women who survived until at least age 70, 1686 (9.9%) met our criteria for healthy survival. Increased body mass index (BMI) at baseline was significantly associated with linearly reduced odds of healthy survival compared with usual survival, after adjustment for various lifestyle and dietary variables (P<0.001 for trend). Compared with lean women (BMI 18.5-22.9), obese women (BMI ≥30) had 79% lower odds of healthy survival (odds ratio 0.21, 95% confidence interval 0.15 to 0.29). In addition, the more weight gained from age 18 until mid-life, the less likely was healthy survival after the age of 70. The lowest odds of healthy survival were among women who were overweight (BMI ≥25) at age 18 and gained ≥10 kg weight (0.18, 0.09 to 0.36), relative to women who were lean (BMI 18.5-22.9) and maintained a stable weight. Conclusions: These data provide evidence that adiposity in mid-life is strongly related to a reduced probability of healthy survival among women who live to older ages, and emphasise the importance of maintaining a healthy weight from early adulthood

Outcomes of cleft palate surgeries at the National Orthopaedic Hospital, Enugu, Nigeria: November 2008 – November 2013

Background: Despite an increase in the number of palatoplasty procedures at the National Orthopaedic Hospital Enugu (NOHE) sequel to a partnership with Smile Train, no reports on subsequent outcomes have been published. We investigated the speech outcomes and rates of fistula formation, the relationship between introduction of solids and incidence of post-operative oronasal fistulae and the benefits of post-operative honey licks. Objective: To determine the outcome of palatal repairs performed at our center in relation to the timing and nature of post-operative feeds. Method: This was a cohort study of patients who had palatoplasty over a five-year period and were subsequently followed up for a maximum period of 9 years. The patient’s present condition, timing of first feeds, onset of solid feeds, honey licks, frequency of wound dehiscence, fistula formation, and speech outcomes were assessed. The evaluation for a fistula was made from two weeks after the surgery by a senior resident in plastic surgery. Analysis was done using SPSS version 21.0 and p value set at &lt;0.05. Results: A total of 115 surgeries: 90 primary cleft palate repairs, 6 combined cleft lip and palate surgeries and 19 secondary cleft palate repairs were done. Male to female ratio was 1:1.3. Age range of patients was 6 weeks to 36 years. Timing of introduction of solid meals significantly affected incidence of repair breakdown; and 58% had normal to near-normal speech. Conclusions: Licking honey was associated with fewer wound breakdowns. Early return to solid feeds is associated with a higher incidence of wound breakdown following palate repair

Evaluation of Microbial and Nutritional Qualities of Aniga and Epiti Moin: Prestige Foods of South Eastern Nigeria

Investigation on the microbiological and nutritional qualities of aniga and epiti moin moin two cultural foods of South eastern Nigeria reveals that the TAPC of aniga ranged from 1.40 x 104 to 1.70 x108cfu/g, the coliform count was < 10 to 2.70 x 104cfu/g and fungal count was 1.60 x 103 to 1.90 x 108cfu/g. Epiti moin moin had a TAPC of 3.40 x 105 to 4.50 x 1010cfu/g, coliform count of 2.00 x 103 to 1.10 x 105cfu/g, and fungal count of 1.17 x 105 to 1.60 x 108cfu/g. The predominant bacterial and fungal isolates included species of Bacillus, Enterobacter, Aspergillus and Saccharomyces. However, species of Corynebacterium, Mucor, and Penicillium were also recovered from epiti moin moin. Varied concentrations of the phytochemicals saponin, tannin, alkaloid, flavonoid, oxalate and cyanide were detected and the proximate analysis shows that aniga and epiti moin moin had moisture contents of 68.55 and 68.41%, Carbohydrate contents of 23.17 and 21.61%, Protein contents of 5.08 and 5.67% and Fat contents of 1.73 and 2.87% respectively. Aniga and Epiti moin moin are rich in nutrients and phytochemicals; they are foods that could be used to augment the nutritional need of man. It is advanced that the application of good manufacturing practices (GMP) and effective hazard analysis critical control point (HACCP) in the production of these foods will be necessary to curtail microbial contaminants, standardize the processing procedures and thus optimize the foods for wider consumer acceptabilit